They're popular because the initial rate is lower, allowing for a higher loan amount. This is expecially advantageous if you don't plan to live in your home for the entire length of the mortgage. They often allow you to refinance to a fixed rate mortgage after a certain amount of time (for a fee, of course) in case the adjustments aren't working to your advantage.

One of the techniques used by the ARM is situational insanity. Many of their agents are paranoids and psychotics. They are treated for their insanity, but while at work, their treatment is withheld, allowing the ARM to have an extra edge, a measure of creativity denied to most organizations. This use of controlled madness saves humanity's collective bacon more than once in the series.

ARM stands for Associate in Risk Management. This is a designation that can be earned by professionals in the insurance industry. The ARM requires a total of three nationally administered tests. The designation also requires that the individual must satisfy a list of ethics, experience, and education requirements.

Arm's end, the end of the arm; a good distance off. Dryden. -- Arm's length, the length of the arm. -- Arm's reach, reach of the arm; the distance the arm can reach. -- To go (or walk) arm in arm, to go with the arm or hand of one linked in the arm of another. "When arm in armwe went along." Tennyson. -- To keep at arm's length, to keep at a distance (literally or figuratively); not to allow to come into close contact or familiar intercourse. -- To work at arm's length, to work disadvantageously.